System for measuring velar function during speech

• US 6,850,882 B1
• Filed: 10/23/2000
• Issued: 02/01/2005
• Est. Priority Date: 10/23/2000
• Status: Expired due to Fees

• Current Assignee: Martin Rothenberg
• Original Assignee: Martin Rothenberg
• Inventors: Rothenberg, Martin
• Primary Examiner(s): ABEBE, DANIEL DEMELASH
• Application Number:
  US09/693,900
• Time in Patent Office: 1,562 Days
• Field of Search: 704/211, 704/200, 704/208, 704/214, 704/271, 704/272, 704/276
• US Class Current: 704/211
• CPC Class Codes: G10L 25/00 Speech or voice analysis techniques not restricted to a single one of groups G10L15/00 - G10L21/00 muting semiconductor-based amplifiers when some special characteristics of a signal are sensed by a speech detector, e.g. sensing when no signal is present, H03G3/34

Abstract

A method of and device for the diagnosis and treatment of speech dynamically measures the functioning of the velum in the control of nasality during speech. Various components of oral and nasal airflow are separated and selectively analyzed including (i) the fundamental frequency component of each airflow during voiced speech, (ii) a plurality of voice components that cover a frequency range encompassing at least the lowest vocal tract resonance (the first formant), and (iii) the subsonic and infrasonic components of at least the nasal airflow. By comparing the nasal and oral airflow components at the voice fundamental frequency, a nasalization measure for voiced speech sounds is formed which emulates methods that compare low frequency nasal and oral airflow during voiced speech, while eliminating or greatly reducing the problems associated with comparing these low frequency airflows, and which improves upon previous methods based on measuring and comparing nasal and oral radiated sound pressure. A circumferentially vented screen mask (C-V mask) is configured with separate nasal and oral chambers to separate the two airflows, and causes only a minimal distortion and muffling of the voice. The separate nasal and oral airflows are detected and filtered, and a ratio of the two is formed to provide a visual display used to detect and correct abnormal or incorrect speech formation and word pronunciation.

Claims

1. An apparatus for indicating speech characteristics comprising:

detectors sensitive to respective oral and nasal airflows to provide respective oral and nasal airflow signals over a predetermined usable frequency response range;

a filter receiving said oral and nasal signals and configured to attenuate energy at frequencies outside a predetermined range of voice frequencies to provide filtered oral d nasal signals;

a processor configured to calculate a ratio value reflecting a ratio of (i) an energy value of said filtered oral signal and (ii) an energy value of said filtered nasal signal; and

a visual display configured to provide an indication of said ratio value,

wherein at least one of said detectors comprises a limiting device for restricting an airflow and a pressure transducer configured to detect an air pressure differential caused by said limiting device.

2. The apparatus according to claim 1 further comprising a mask shaped to simultaneously cover the mouth and nose of a subject and having separate oral and nasal chambers for directing respective said oral and nasal airflows.

3. The apparatus according to claim 2 wherein said mask comprises a dual oral/nasal circumferentially vented screen mask having pressure microphones respectively coupled to said oral and nasal chambers of said mask.

4. The apparatus according to claim 1 wherein said detectors comprise respective oral and nasal airflow transducers.

5. The apparatus according to claim 1 wherein said detectors comprise respective velocity-sensitive microphones.

6. The apparatus according to claim 1 further comprising a converter receiving said filtered oral and nasal signals to provide a digital format signal, and a digital computer responsive to a stored program of instructions and comprising said filter and said processor.

7. The apparatus according to claim 1 further comprising a signal differentiator configured for proving a value representing a time rate of change of said oral and nasal airflow signals.

8. The apparatus according claim 1 further comprising a memory storing idealized templates representing normal speech corresponding to predetermined utterances.

9. The apparatus according to claim 1 further comprising a processor configured to calculate a ratio represented by said low frequency component of said nasal airflow divided by a sum of (a) a low frequency component of said oral airflow plus (b) said low frequency component of said nasal airflow.

10. The apparatus according to claim 1 further including an audio reproduction device storing and reproducing audio frequency components of said oral airflow signal.

11. An apparatus for measuring the degree of closure of the oronasal passageway during speech comprising:

a mask shaped to simultaneously cover the mouth and nose of a subject and having separate oral and nasal chambers for directing respective oral and nasal airflows;

oral and nasal transducers in respective communication with said oral and nasal chambers, each of said oral and nasal transducers operative to respectively detect said oral and nasal airflows to provide respective oral and nasal airflow signals over a predetermined usable frequency response range;

oral and nasal signal bandpass filters respectively receiving said oral and nasal airflow signals from said oral and nasal transducers and supplying respective filtered oral and nasal signals in which energy at frequencies outside a predetermined voice fundamental frequency range is substantially attenuated;

a comparator providing a ratio value reflecting a ratio of (i) an energy value of said filtered nasal signal and (ii) an energy value of said filtered oral signal; and

a display providing an indication of said ratio value, wherein

a frequency response range of said oral and nasal transducers includes a predetermined multiplicity of human voice harmonics up to and including 800 Hz; and

bandpasses of said oral and nasal signal bandpass filters include at least a lowest formant of the human vocal tract for most vowels produced by the class of speakers for which the apparatus is intended, said oral and nasal signal bandpass filters each having lower and upper frequency half-power points of approximately 300 and 700 Hz, respectively.

12. The apparatus according to claim 11 wherein said mask is a dual oral/nasal circumferentially vented screen mask and said oral and nasal transducers are pressure microphones respectively coupled to said oral and nasal chambers of said mask.

13. The apparatus according to claim 11 wherein said oral and nasal airflow signals are supplied to an analog-to-digital converter of a digital computer and said (i) oral and nasal signal bandpass filters, (ii) comparator, and (iii) display are implemented by program instructions executed by said digital computer, an output of said display being provided on a computer monitor.

14. The apparatus according to claim 11 wherein:

a frequency response range of said oral and nasal transducers includes an expected range of voice fundamental frequencies which can be 75-350 Hz for speech; and

bandpasses of said oral and nasal signal bandpass filters that can be chosen to match the fundamental frequency range of a particular speaker.

15. The apparatus according to claim 11, wherein said oral and nasal signal bandpass filters each have lower and upper half-power points within the ranges of 200 to 450 Hz and 550 to 800 Hz, respectively.

16. The apparatus according to claim 11, wherein said oral and nasal signal bandpass filters each have lower and upper half-power points within the respective ranges of 200 to 450 Hz and 550 to 800 Hz, respectively.

17. The apparatus according to claim 11, wherein at least one of said oral and nasal signal bandpass filters has a nominal lower half-power point of 350 Hz and an upper half power point of 650 Hz, respectively.

18. The apparatus according to claim 11, wherein said oral and nasal bandpass filters each include a signal differentiator operable to provide a signal representing changes in said oral and nasal airflow signals with respect to time within the passband of the filters.

19. The apparatus according to claim 11 further comprising an audio signal recorder configured for storing and reproducing audio frequency components of said oral airflow signal corresponding to speech sounds.

20. The apparatus according to claim 11 further comprising an audio signal recorder configured for storing and reproducing audio frequency components of said oral and nasal airflow signals corresponding to speech sounds.

21. The apparatus according to claim 20 further comprising a controller operative to synchronize functioning of said display and said audio signal recorder.

22. An apparatus for measuring the degree of closure of the oronasal passageway during speech comprising:

a mask shaped to simultaneously cover the mouth and nose of a subject and having separate oral and nasal chambers for directing respective oral and nasal airflows;

oral and nasal transducers in respective communication with said oral and nasal chambers, each of said oral and nasal transducers operative to respectively detect said oral and nasal airflows to provide respective oral and nasal airflow signals over a predetermined usable frequency response range;

oral and nasal signal bandpass filters respectively receiving said oral and nasal airflow signals from said oral and nasal transducers and supplying respective filtered oral and nasal signals in which energy at frequencies outside a predetermined voice fundamental frequency range is substantially attenuated;

a comparator providing a ratio value reflecting a ratio of (i) an energy value of said filtered nasal signal and (ii) an energy value of said filtered oral signal;

a display providing an indication of said ratio value;

a low frequency nasal chamber transducer configured for providing a nasal low frequency signal corresponding to low frequency airflow components of said nasal airflow including the zero frequency (constant flow) component; and

a low frequency lowpass filter configured to attenuate voice frequency energy from an output of said low frequency nasal chamber transducer.

23. The apparatus according to claim 22 wherein said low frequency bandpass filter has a high frequency half power point within a range of 20 to 40 Hz.

24. The apparatus according to claim 22 further comprising a low frequency oral chamber transducer configured to provide an oral low frequency signal corresponding to low frequency airflow components of said oral airflow.

25. The apparatus according to claim 24 further comprising a low frequency comparator configured for computing a ratio of a value of said nasal low frequency signal to a value of said oral low frequency signal.

26. The apparatus according to claim 25 wherein said low frequency comparator includes means for computing (i) said value of said nasal low frequency signal divided by (ii) a value representing a sum of (a) said value of said oral low frequency signal plus (b) said value of said nasal low frequency signal.

27. The apparatus according to claim 26 further comprising a controller operative to synchronize functioning of said display and said audio signal recorder.

28. The apparatus according to claim 22 further comprising a low frequency display providing an indication of said low frequency airflow components of said nasal airflow.

29. An apparatus for measuring the degree of closure of the oronasal passageway during speech comprising:

a mask shaped to simultaneously cover the mouth and nose of a subject and having separate oral and nasal chambers for directing respective oral and nasal airflows;

oral and nasal transducers in respective communication with said oral and nasal chambers, each of said oral and nasal transducers operative to respectively detect said oral and nasal airflows to provide respective oral and nasal airflow signals over a predetermined usable frequency response range;

oral and nasal signal bandpass filters respectively receiving said oral and nasal airflow signals from said oral and nasal transducers and supplying respective filtered oral and nasal signals in which energy at frequencies outside a predetermined voice fundamental frequency range is substantially attenuated;

a comparator providing a ratio value reflecting a ratio of (i) an energy value of said filtered nasal signal and (ii) an energy value of said filtered oral signal;

a display providing an indication of said ratio value;

a low frequency transducer means for measuring low frequency airflow components of at least one of (i) said nasal airflow and (ii) both said nasal and oral airflows, including the zero frequency (constant flow) components; and

low frequency filtering means for attenuating voice frequency energy from the outputs of said low frequency transducer means and having upper frequency half-power points within a range of 20 to 40 Hz.

30. The apparatus according to claim 29 further comprising a low frequency nasal airflow comparison and display means that determines the periods of time during which the low frequency nasal airflow is greater than a predetermined level deemed not acceptable and the voiced nasal airflow is lower than a predetermined level deemed to indicate the presence of voicing, and present to the user a display feature indicating the presence of unvoiced nasal emissions during the said periods of time.

31. The apparatus according to claim 30 wherein the said indicating feature includes an indication of a level on a numerical scale of either (i) the level of unvoiced nasal airflow, or (ii) a quantity comparing said nasal airflow to said oral airflow.

32. The apparatus according to claim 29 further comprising low frequency comparison means for computing a ratio of (i) said low frequency airflow components of said nasal airflow and (ii) said low frequency airflow component of said oral airflow.

33. The apparatus according to claim 30 wherein said low frequency comparison means includes means for computing a ratio of (i) said low frequency airflow components of said nasal airflow divided by (ii) a sum representing said low frequency airflow components of said nasal and oral airflows.

34. A method of measuring the degree of closure of the oronasal passageway during speech comprising the steps of:

detecting oral and nasal airflows to provide respective oral and nasal airflow signals over a predetermined usable frequency response range;

filtering said oral and nasal signals to attenuate energy at frequencies outside a predetermined range of voice frequencies so as to provide filtered oral and nasal signals and attenuate signals having a frequency outside of a range of approximately 200 to 800 Hz;

calculating a ratio value reflecting a ratio of (i) an energy value of said filtered oral signal and (ii) an energy value of said filtered nasal signal; and

displaying an indication of said ratio value.

35. The method according to claim 34 further comprising a step of simultaneously covering the mouth and nose of a subject with a mask having separate oral and nasal chambers for directing respective said oral and nasal airflows.

36. The method according to claim 34 further comprising a step of providing a dual oral/nasal circumferentially vented screen mask having pressure microphones respectively coupled to said oral and nasal chambers of said mask.

37. The method according to claim 34 further comprising the steps of converting said filtered oral and nasal signals to a digital format and wherein said steps of filtering and calculating are performed by a digital computer in response to a stored program of instructions.

38. The method according to claim 34 wherein said filtering step attenuates energy not at the voice fundamental frequency.

39. The method according to claim 38 further comprising measurement of the amplitudes of the outputs of the filtering step.

40. The method according to claim 34 further comprising a step of differentiating said oral and nasal airflow signals with respect to time.

41. The method according to claim 40 further comprising measurement of the amplitudes of the outputs of the filtering step.

42. The method according to claim 34 further comprising measurement of the amplitudes of the outputs of the filtering step.

43. The method according to claim 34 further including steps storing and reproducing audio frequency components of said oral airflow signal.

44. A method of measuring the degree of closure of the oronasal passageway during speech comprising the steps of:

detecting oral and nasal airflows to provide respective oral and nasal airflow signals over a predetermined usable frequency response range;

filtering said oral and nasal signals to attenuate energy at frequencies outside a predetermined range of voice frequencies so as to provide filtered oral and nasal signals;

calculating a ratio value reflecting a ratio of (i) an energy value of said filtered oral signal and (ii) an energy value of said filtered nasal signal;

displaying an indication of said ratio value;

detecting a low frequency component of said nasal airflow;

providing a low frequency nasal signal in response to said detecting step; and

lowpass filtering said low frequency nasal signal to attenuate the voice frequency energy.

45. The method according to claim 44 wherein said step of filtering said low frequency nasal signal attenuates signals having a frequency of greater than 40 Hz by at least 3 dB.

46. The method according to claim 44 further comprising a step of calculating a ratio of said low frequency component of said nasal airflow divided by a low frequency component of said sum of (a) a low frequency component of said oral airflow plus (b) said low frequency component said nasal airflow.