Hearing aid employing adjustment of the intensity and the arrival time of sound by electronic or acoustic, passive devices to improve interaural perceptual balance and binaural processing

• US 5,434,924 A
• Filed: 03/06/1991
• Issued: 07/18/1995
• Est. Priority Date: 05/11/1987
• Status: Expired due to Term

• Current Assignee: Jay Management Trust
• Original Assignee: Jay Management Trust
• Inventors: Jampolsky, Arthur
• Primary Examiner(s): Kuntz, Curtis
• Assistant Examiner(s): CUMMING, WILLIAM D
• Application Number:
  US07/666,477
• Time in Patent Office: 1,595 Days
• Field of Search: 128/731, 381/68.4, 381/68.1, 381/68.5, 381/68.7, 381/68, 381/69, 381/23.1, 381/28, 381/68.2, 381/68.3, 381/17, 381/25
• US Class Current: 381/23.1
• CPC Class Codes: H04R 25/502 using analog signal processing
• CPC Class Codes: H04R 25/552 Binaural
• CPC Class Codes: H04S 1/00 Two-channel systems H04S5/00, H04S7/00 take precedence

Abstract

A hearing aid for a person with asymmetric hearing perception (a weaker ear system and a better ear system) employs conventional frequency-selective amplification (26L) of sound coming to the weaker ear'"'"'s system and frequency selective amplitude adjustment (32) and arrival time adjustment (retardation or relative advancement) (34) of sound coming to the better ear'"'"'s system so that its resultant characteristics match those of the weaker ear'"'"'s system, as aided, or even without aiding the weaker ear'"'"'s system. As a result, sound perceived by both ear systems is matched or balanced, at each frequency, in both arrival time and amplitude. Such interaural balancing effects a great improvement in the binural processing mechanism, which in turn increases speech perception, especially in the presence of general noise or adjacent localized noise sources. The aid may be implemented by a pair of microphones (24L, 24R), one for each ear'"'"'s system. The signal from the microphone to the weaker ear'"'"'s system includes a conventional variable gain amplifier (26L) and a conventional frequency selective filter (13) to provide tailored amplification of the sound to the weaker ear'"'"'s system, insofar as possible. Also the channel to the weaker ear'"'"'s system includes a fixed delay (28) to compensate for a delay in the channel to the better ear'"'"'s system. The signal from the microphone to the better ear'"'"'s system includes a variable gain amplifier (26R) and a set of bandpass filters (30) to cover the audio spectrum in discrete steps. Each filter is connected in series with a selected attenuator (32) and a selected time delay (34) so as to match the perceived arrival time and amplitude level at its band with that of the weaker ear'"'"'s system.

Claims

1. A method for improving binaural hearing balance of a person with two functioning ear systems, one of which has hearing perception which is poorer than hearing perception in said person'"'"'s other and better ear system, said method comprising:

(a) determining differences in binaurally perceived intensities and in binaurally perceived sound arrival times between such person'"'"'s left and right ear systems so as to determine a difference in hearing perception between said person'"'"'s two ear systems, and

(b) adjusting (1) intensity of sound to at least one of said person'"'"'s ear systems, and (2) arrival time of sound to at least one of said person'"'"'s ear systems in accordance with said determined differences in binaurally perceived intensities and binaurally perceived sound arrival times between such person'"'"'s two ear systems such as to decrease said differences and achieve better interaural balance between said person'"'"'s two ear systems,

thereby to improve interaural perceptual balance between said person'"'"'s two ear systems and binaural processing of said person, and thus improve said person'"'"'s hearing, including speech perception, for different environments and different sound levels.

2. The method of claim 1 wherein said adjusting is done as a function of frequency.

3. The method of claim 1 wherein said adjusting is done to said person'"'"'s poorer ear system.

4. The method of claim 1 wherein said adjusting is performed by passive means.

5. The method of claim 1 wherein:

(a) said determining differences is done with objective means for indicating when improved hearing balance is achieved between said person'"'"'s two ear systems by determining functional activity in said person'"'"'s nervous system, said objective means comprising an external instrument,

(b) said objective means is used to determine, in said person'"'"'s nervous system, optimal functional activity which indicates improved hearing balance,

whereby said determining can be done with infants and adults, or mentally impaired patients and other patients who cannot sufficiently communicate their perceptual responses, so that said determination of optimal functional activity can be used to provide a hearing aid which improves binaural balance.

6. The method of claim 1 wherein said adjusting is further done so that when said person hears a single sound source which emits sounds at a plurality of different frequencies, said person will perceive said sounds at said plurality of different frequencies as all appearing to come from substantially one location in space.

7. A binaural hearing aid for improving binaural hearing balance in a person with two functioning ear systems, one of which has hearing perception which is poorer than the hearing perception in said person'"'"'s other and better ear system, said binaural hearing aid comprising:

(a) sound-receiving means for receiving sound to at least one of said person'"'"'s ear systems, and

(b) sound-adjusting means for adjusting (1) intensity of received sound to at least one of said person'"'"'s two ear systems, and (2) arrival time of received sound to at least one of said person'"'"'s two ear systems,

(c) said sound-adjusting means being arranged to decrease perceived interaural differences in arrival times and intensities of said received sound between said person'"'"'s two ear systems and achieve improved interaural hearing balance in perceived arrival times and intensities between said person'"'"'s two ear systems,

thereby to improve binaural processing of said person and thus improve said person'"'"'s hearing, including speech perception, for different environments and different sound levels.

8. The hearing aid of claim 7 wherein said sound-adjusting means adjusts said intensity and said arrival time as a function of frequency.

9. The hearing aid of claim 7, further including additional sound-adjusting means for adjusting sound to said person'"'"'s poorer ear system.

10. The hearing aid of claim 7 wherein said sound-adjusting means comprises means for separating received sound into a plurality of separate frequency bands, and means for selectively adjusting perceived arrival times and perceived intensities of said sound in said separate frequency bands.

11. The hearing aid of claim 10 wherein said sound-receiving means comprises a microphone, said means for separating received sound into separate frequency bands comprises a plurality of filters, and said means for selectively adjusting perceived arrival times and intensifies of sound in said separate frequency bands comprises a plurality of attenuators and delays.

12. The hearing aid of claim 7, further including a pair of ear housings, said sound-receiving means and said sound-adjusting being mounted within said pair of ear housings, and further including coupling means for coupling signals from within one of said housings to within the other of said housings, said means for coupling signals comprising a wireless link.

13. The hearing aid of claim 7, further including:

(a) objective means for indicating when improved hearing balance is achieved between said person'"'"'s two ear systems by determining functional activity in said person'"'"'s nervous system,

(b) said objective means comprising an external instrument,

(c) said objective means being usable with said sound-adjusting means for determining, in said person'"'"'s nervous system, optimal functional activity which indicates improved hearing balance,

whereby said objective means can be used with infants and adults, or mentally impaired patients and other patients who cannot sufficiently communicate their perceptual responses, so that said determination of optimal functional activity can be used to provide a hearing aid which improves binaural balance.

14. A method for improving binaural hearing balance of a person with two functioning ear systems, one of which has hearing perception which is poorer than hearing perception in said person'"'"'s other and better ear system, said method comprising:

(a) adjusting arrival time of sound to at least one of said person'"'"'s ear systems by an amount less than one millisecond, and

(b) adjusting intensity of sound to at least one of said person'"'"'s ear systems,

(c) said adjusting of said arrival time and said intensity being arranged to decrease perceived interaural differences in arrival times and intensities between said person'"'"'s two ear systems and achieve improved interaural hearing balance in perceived arrival times and intensities between said person'"'"'s two ear systems,

thereby to improve interaural perceptual balance between said person'"'"'s two ear systems and binaural processing of said person, and thus improve said person'"'"'s hearing, including speech perception, for different environments and different sound levels.

15. The method of claim 14 wherein said adjusting is done as a function of frequency.

16. The method of claim 14, further including:

(a) providing objective means for indicating when improved hearing balance is achieved between said person'"'"'s two ear systems by determining functional activity in said person'"'"'s nervous system, said objective means comprising an external instrument, and

(b) using said objective means while said sound is being adjusted to determine, in said person'"'"'s nervous system, optimal functional activity which indicates improved hearing balance,

whereby said determining can be done with infants and adults, or mentally impaired patients and other patients who cannot sufficiently communicate their perceptual responses, so that said determination of optimal functional activity can be used to provide a hearing aid which improves binaural balance.

17. The method of claim 14 wherein said adjusting is further done so that when said person hears a single sound source which emits sounds at a plurality of different frequencies, said person will perceive said sounds at said plurality of different frequencies as all appearing to come from substantially one location in space.

18. A method for improving binaural hearing balance in a person with two functioning ear systems, one of which has hearing perception which is poorer than hearing perception in said person'"'"'s other and better ear system, said method comprising:

(a) receiving sound to at least one of said person'"'"'s ear systems, and

(b) adjusting arrival time of received sound to said one of said person'"'"'s ear systems by less than one millisecond,

(c) said adjusting of said arrival time of said received sound being arranged to decrease perceived interaural differences in arrival times of said received sound between said person'"'"'s two ear systems and achieve improved interaural hearing balance in perceived arrival times between said person'"'"'s two ear systems,

thereby to improve binaural processing of said person, and thus improve said person'"'"'s hearing, including speech perception, for different environments and different sound levels.

19. The method of claim 18 wherein said adjusting is done as a function of frequency.

20. The method of claim 18, further including:

(a) providing objective means for indicating when improved hearing balance is achieved between said person'"'"'s two ear systems by determining functional activity in said person'"'"'s nervous system, said objective means comprising an external instrument, and

(b) using said objective means while said sound is being adjusted to determine, in said person'"'"'s nervous system, optimal functional activity which indicates improved hearing balance,

whereby said determining can be done with infants and adults, or mentally impaired patients and other patients who cannot sufficiently communicate their perceptual responses, so that said determination of optimal functional activity can be used to provide a hearing aid which improves binaural balance.

21. The method of claim 18 wherein said adjusting is further done so that when said person hears a single sound source which emits sounds at a plurality of different frequencies, said person will perceive said sounds at said plurality of different frequencies as all appearing to come from substantially one location in space.

22. A method for improving binaural hearing balance of a person with two functioning ear systems, one of which has hearing perception which is poorer than hearing perception in said person'"'"'s other and better ear system, said method comprising:

(a) receiving sound to at least one of said person'"'"'s ear systems, and

(b) adjusting intensity of received sound as a function of frequency to said one of said person'"'"'s ear systems,

(c) said adjusting intensity of received sound being done so that when sound at a plurality of different frequencies emanating from a single source reaches said person'"'"'s two ear systems, said person will have a decrease in perceived interaural difference in intensities of said received sound between said person'"'"'s two ear systems and achieve improved interaural hearing balance in perceived intensities between said person'"'"'s two ear systems,

thereby to achieve simultaneous, interactive binaural processing at said plurality of different frequencies, with said person'"'"'s two ear systems being centrally coordinated, and

thereby to improve interaural perceptual balance and binaural processing of said person, and thus improve said person'"'"'s hearing, including speech perception, for different environments and different sound levels.

23. The method of claim 22, further including:

(a) providing objective means for indicating when improved heating balance is achieved between said person'"'"'s two ear systems by determining functional activity in said person'"'"'s nervous system, said objective means comprising an external instrument, and

(b) using said objective means while said sound is being adjusted to determine, in said person'"'"'s nervous system optimal functional activity which indicates improved hearing balance,

whereby said determining can be done with infants and adults, or mentally impaired patients and other patients who cannot sufficiently communicate their perceptual responses, so that said determination of optimal functional activity can be used to provide a hearing aid which improves binaural balance.

24. The method of claim 22 wherein said adjusting is further done so that when said person hears a single sound source which emits sounds at a plurality of different frequencies, said person will perceive said sounds at said plurality of different frequencies as all appearing to come from substantially one location in space.

25. A method for improving binaural hearing balance of a person with two functioning ear systems, one of which has hearing perception which is poorer than hearing perception in said person'"'"'s other and better ear system, comprising:

(a) receiving sound to at least one of said person'"'"'s ear systems, and

(b) adjusting (1) intensity of received sound to said one of said person'"'"'s ear systems, and (2) arrival time of received sound to said one of said person'"'"'s ear systems,

(c) said adjusting of said intensity and arrival time of said received sound being arranged to decrease perceived interaural differences in intensities and arrival times between said person'"'"'s two ear systems and achieve improved interaural hearing balance in perceived intensities and arrival times of said received sound between said person'"'"'s two ear systems, and such as to cause perceived interaural intensities and perceived arrival times of sound in said person'"'"'s two ear systems to be closer together,

thereby to improve interaural perceptual balance and binaural processing of said person, and thus improve said person'"'"'s hearing, including speech perception, for different environments and different sound levels.

26. The method of claim 25, further including a step of determining differences in perceived intensities and perceived sound arrival times of sound between said person'"'"'s left and right ear systems so as to determine a difference in hearing between said person'"'"'s two ear systems, and wherein said adjusting is done so as to reduce said differences between said person'"'"'s left and right ear systems.

27. The method of claim 26 wherein:

(a) said determining differences is done with objective means for indicating when improved hearing balance is achieved between said person'"'"'s two ear systems by determining functional activity in said person'"'"'s nervous system, said objective means comprising an external instrument,

(b) said objective means is used to determine, in said person'"'"'s nervous system, optimal functional activity which indicates improved hearing balance,

whereby said determining can be done with infants and adults, or mentally impaired patients and other patients who cannot sufficiently communicate their perceptual responses, so that said determination of optimal functional activity can be used to provide a hearing aid which improves binaural balance.

28. The method of claim 27 wherein said adjusting is performed as a function of frequency.

29. The method of claim 27 wherein said adjusting is further done so that when said person hears a single sound source which emits sounds at a plurality of different frequencies, said person will perceive said sounds at said plurality of different frequencies as all appearing to come from substantially one location in space.

30. A binaural hearing aid for improving binaural hearing balance in a person with two functioning ear systems, one of which has hearing perception which is poorer than hearing perception in said person'"'"'s other and better ear system, said binaural hearing aid comprising:

(a) sound-receiving means for receiving sound to at least one of said person'"'"'s ear systems, and

(b) sound-adjusting means for adjusting (1) intensity of received sound said one of said person'"'"'s two ear systems so as to bring perceived intensities of said received sound to said person'"'"'s two ear systems closer together, and (2) arrival time of said received sound to said one of said person'"'"'s two ear systems so as to bring perceived arrival times of received sound to said person'"'"'s two ear systems closer together,

thereby to improve interaural perceptual balance between said person'"'"'s two ear systems and binaural processing of said person, and thus improve said person'"'"'s hearing, including speech perception, for different environments and different sound levels.

31. The hearing aid of claim 30 wherein said means for adjusting adjusts said intensity and said arrival time as a function of frequency.

32. The method of claim 30 wherein said adjusting is further done so that when said person hears a single sound source which emits sounds at a plurality of different frequencies, said person will perceive said sounds at said plurality of different frequencies as all appearing to come from substantially one location in space.

33. The hearing aid of claim 30, further including:

(a) objective means for indicating when improved hearing balance is achieved between said person'"'"'s two ear systems by determining functional activity in said person'"'"'s nervous system,

(b) said objective means comprising an external instrument,

(c) said objective means being usable with said sound-adjusting means for determining, in said person'"'"'s nervous system, optimal functional activity which indicates improved hearing balance,

whereby said objective means can be used with infants and adults, or mentally impaired patients and other patients who cannot sufficiently communicate their perceptual responses, so that said determination of optimal functional activity can be used to provide a heating aid which improves binaural balance.

34. A method for improving binaural hearing balance of a person with two functioning ear systems, one of which has hearing perception which is poorer than hearing perception in said person'"'"'s other and better ear system, said method comprising:

(a) receiving sound to at least one of said person'"'"'s ear systems, and

(b) adjusting arrival time of sound to said one of said person'"'"'s ear systems,

(c) said adjusting arrival time of sound being less than one millisecond,

(d) said adjusting arrival time of sound also being selected so as to cause said person to perceive sounds within said person'"'"'s ear systems as coming from a more symmetrical location with respect to said person than without said adjustment,

thereby to improve interaural perceptual balance between said person'"'"'s two ear systems and binaural processing of said person, and thus improve said person'"'"'s hearing, including speech perception, for different environments and different sound levels.

35. The method of claim 34, further including:

(a) providing objective means for indicating when improved hearing balance is achieved between said person'"'"'s two ear systems by determining functional activity in said person'"'"'s nervous system, said objective means comprising an external instrument, and

(b) using said objective means while said sound is being adjusted to determine, in said person'"'"'s nervous system, optimal functional activity which indicates improved hearing balance,

whereby said determining can be done with infants and adults, or mentally impaired patients and other patients who cannot sufficiently communicate their perceptual responses, so that said determination of optimal functional activity can be used to provide a hearing aid which improves binaural balance.

36. A method for improving binaural hearing balance in a person with two functioning ear systems, one of which has hearing perception which is poorer than hearing perception in said person'"'"'s other and better ear system, said method comprising:

(a) receiving sound to at least one of said person'"'"'s ear systems, and

(b) adjusting intensity of received sound to said one of said person'"'"'s ear systems at a plurality of different frequencies in a manner so that when said person hears a single sound source which emits sounds at a plurality of different frequencies, said person will perceive said received sounds at said plurality of different frequencies as all appearing to come from substantially one location in space and said person will experience simultaneous, interactive, binaural processing at said plurality of different frequencies, with said person'"'"'s two ear systems being centrally coordinated,

thereby to improve said person'"'"'s interaural perceptual balance and binaural processing, and thus improve said person'"'"'s hearing, including speech perception, for different environments and different sound levels.

37. The method of claim 36, further including:

(a) providing objective means for indicating when improved hearing balance is achieved between said person'"'"'s two ear systems by determining functional activity in said person'"'"'s nervous system, said objective means comprising an external instrument, and

(b) using said objective means while said sound is being adjusted to determine optimal functional activity in said person'"'"'s nervous system which indicates improved hearing balance,

whereby said determining can be done with infants and adults, or mentally impaired patients and other patients who cannot sufficiently communicate their perceptual responses, so that said determination of optimal functional activity can be used to provide a hearing aid which improves binaural balance.

38. A binaural hearing aid for improving binaural hearing balance in a person with two functioning ear systems, one of which has hearing perception which is poorer than the hearing perception in said person'"'"'s other and better ear system, said binaural hearing aid comprising:

(a) sound-receiving means for receiving sound to at least one of said person'"'"'s ear systems, and

(b) sound-adjusting means for adjusting (1) intensity of received sound to at least one of said person'"'"'s two ear systems as a function of frequency, and (2) arrival time of received sound to at least one of said person'"'"'s two ear systems as a function of frequency, so that when said person hears a single sound source which emits sounds at a plurality of different frequencies, said person will perceive received sounds at said plurality of different frequencies as all appearing to come from substantially one location in space,

thereby to improve interaural perceptual balance between said person'"'"'s two ear systems and binaural processing of said person, and thus improve said person'"'"'s hearing, including speech perception, for different environments and different sound levels.

39. The method of claim 38, further including:

(a) objective means for indicating when improved hearing balance is achieved between said person'"'"'s two ear systems by determining functional activity in said person'"'"'s nervous system,

(b) said objective means comprising an external instrument,

(c) said objective means being usable with said sound-adjusting means for determining, in said person'"'"'s nervous system, optimal functional activity which indicates improved hearing balance,

whereby said objective means can be used with infants and adults, or mentally impaired patients and other patients who cannot sufficiently communicate their perceptual responses, so that said determination of optimal functional activity can be used to provide a hearing aid which improves binaural balance.

40. A binaural hearing aid for improving binaural hearing balance in a person with two functioning ear systems, one of which has hearing perception which is poorer than the hearing perception in said person'"'"'s other and better ear system, said binaural hearing aid comprising:

(a) sound-receiving means for receiving sound to at least one of said person'"'"'s ear systems, and

(b) sound-adjusting means for adjusting arrival time of received sound to said one of said person'"'"'s two ear systems as a function of frequency such that when said person hears a single sound source which emits sounds at a plurality of different frequencies, said person will perceive said sounds at said plurality of different frequencies as all appearing to come from substantially one location in space,

thereby to improve interaural perceptual balance between said person'"'"'s two ear systems and binaural processing of said person, and thus improve said person'"'"'s hearing, including speech perception, for different environments and different sound levels.

41. The hearing aid of claim 40, further including:

(a) objective means for indicating when improved hearing balance is achieved between said person'"'"'s two ear systems by determining functional activity in said person'"'"'s nervous system,

(b) said objective means comprising an external instrument,

(c) said objective means being usable with said sound-adjusting means for determining, in said person'"'"'s nervous system, optimal functional activity which indicates improved hearing balance,

whereby said objective means can be used with infants and adults, or mentally impaired patients and other patients who cannot sufficiently communicate their perceptual responses, so that said determination of optimal functional activity can be used to provide a hearing aid which improves binaural balance.

42. A binaural hearing aid for improving binaural hearing balance in a person with two functioning ear systems, one of which has hearing perception which is poorer than the hearing perception in said person'"'"'s other and better ear system, said binaural hearing aid comprising:

(a) sound-receiving means for receiving sound to at least one of said person'"'"'s ear systems, and

(b) sound-adjusting means for adjusting (1) intensity of received sound at a plurality of frequencies to said one ear system, and (2) arrival time of received sound at a plurality of frequencies to said one ear system such as to decrease said person'"'"'s perceived interaural differences and improve said person'"'"'s binaural processing and said person'"'"'s hearing, including speech perception, for different environments and different sound levels at said plurality of frequencies.

43. The hearing aid of claim 42, further including:

(a) objective means for indicating when improved hearing balance is achieved between said person'"'"'s two ear systems by determining functional activity in said person'"'"'s nervous system,

(b) said objective means comprising an external instrument,

(c) said objective means being usable with said sound-adjusting means for determining, in said person'"'"'s nervous system, optimal functional activity which indicates improved hearing balance,

whereby said objective means can be used with infants and adults, or mentally impaired patients and other patients who cannot sufficiently communicate their perceptual responses, so that said determination of optimal functional activity can be used to provide a hearing aid which improves binaural balance.

44. A method for improving binaural hearing balance of a person with two functioning ear systems, one of which has hearing perception which is poorer than hearing perception in said person'"'"'s other and better ear system, said method comprising:

(a) receiving sound to at least one of said person'"'"'s ear systems, and

(b) adjusting arrival time of sound to said one of said person'"'"'s ear systems at a plurality of different frequencies so as to decrease perceived interaural differences in arrival times between said person'"'"'s two ear systems and achieve improved interaural hearing balance in perceived arrival times between said person'"'"'s two ear systems,

thereby to improve interaural perceptual balance between said person'"'"'s two ear systems and binaural processing of said person, and thus improve said person'"'"'s hearing, including speech perception, for different environments and different sound levels.

45. The method of claim 44, further including:

(a) providing objective means for indicating when improved hearing balance is achieved between said person'"'"'s two ear systems by determining functional activity in said person'"'"'s nervous system, said objective means comprising an external instrument, and

(b) using said objective means while said sound is being adjusted to determine, in said person'"'"'s nervous system, optimal functional activity which indicates improved hearing balance,

whereby said determining can be done with infants and adults, or mentally impaired patients and other patients who cannot sufficiently communicate their perceptual responses, so that said determination of optimal functional activity can be used to provide a hearing aid which improves binaural balance.

46. A method for improving binaural hearing balance of a person with two functioning ear systems, one of which has hearing perception which is poorer than hearing perception in said person'"'"'s other and better ear system, said method comprising:

(a) receiving sound to at least one of said person'"'"'s ear systems,

(b) providing objective means for indicating when improved hearing balance is achieved between said person'"'"'s two ear systems by determining functional activity in said person'"'"'s nervous system, said objective means comprising an external instrument,

(c) adjusting intensity of received sound to said one of said one of said person'"'"'s ear systems at a plurality of different frequencies,

(d) said intensity adjustment being done while using said objective means to determine optimal functional activity in said person'"'"'s nervous system which indicates improved hearing balance,

whereby said adjusting can be done with infants and adults, or mentally impaired patients and other patients who cannot sufficiently communicate their perceptual responses, so that said determination of optimal functional activity can be used to provide a hearing aid which improves binaural balance and so that said person'"'"'s hearing, including speech perception, will be improved for different environments and different sound levels.

47. A method for improving binaural hearing balance of a person with two functioning ear systems, one of which has hearing perception which is poorer than hearing perception in said person'"'"'s other and better ear system, said method comprising:

(a) receiving sound to at least one of said person'"'"'s ear systems, and

(b) adjusting (1) arrival time of sound to said one of said person'"'"'s ear systems at a plurality of frequencies, and (2) intensity of sound to said one of said person'"'"'s ear systems at said plurality of frequencies,

(c) said adjusting being such that when said person hears a single sound source which emits sounds at a plurality of different frequencies, said person will perceive said sounds at said plurality of different frequencies as all appearing to come from substantially one location in space,

thereby to improve interaural perceptual balance between said person'"'"'s two ear systems and binaural processing of said person, and thus improve said person'"'"'s hearing, including speech perception, for different environments and different sound levels.

48. The method of claim 47, further including:

(a) providing objective means for indicating when improved hearing balance is achieved between said person'"'"'s two ear systems by determining functional activity in said person'"'"'s nervous system, said objective means comprising an external instrument, and

(b) using said objective means while said sound is being adjusted to determine optimal functional activity in said person'"'"'s nervous system which indicates improved hearing balance,

whereby said determining can be done with infants and adults, or mentally impaired patients and other patients who cannot sufficiently communicate their perceptual responses, so that said determination of optimal functional activity can be used to provide a hearing aid which improves binaural balance.

49. A method for determining conditions for achieving improved binaural balance in hearing between a person'"'"'s ear systems, wherein said person has two functioning ear systems, one of which has hearing perception which is poorer than hearing perception in said person'"'"'s other and better ear system, said method comprising:

(a) providing objective means for indicating when improved hearing balance is achieved between said person'"'"'s two ear systems by determining functional activity in said person'"'"'s nervous system, said objective means comprising an external instrument,

(b) adjusting sound to at least one of said person'"'"'s ear systems, and

(c) using said objective means while said sound is being adjusted to determine optimal functional activity in said person'"'"'s nervous system which indicates improved hearing balance,

whereby said determining can be done with infants and adults, or mentally impaired patients and other patients who cannot sufficiently communicate their perceptual responses, so that said determination of optimal functional activity can be used to provide a hearing aid which improves binaural balance.

50. The method of claim 49 wherein said adjusting sound is used to adjust arrival time of sound.

51. The method of claim 49 wherein said adjusting sound is used to adjust intensity of sound.

52. The method of claim 49 wherein said adjusting sound is used to adjust arrival time and intensity of sound.

53. The method of claim 49 wherein said adjusting sound is done as a function of frequency of said sound.

54. The method of claim 49 wherein said adjusting sound is used to adjust intensity of sound as a function of frequency of said sound.