Stethoscope-type recording system with stretched-in-time playback
First Claim
1. Apparatus for reproducing sounds stretched-in-time comprising:
- sound transducer means for picking up audible sounds and generating corresponding electrical signals;
means for processing said electrical signals to develop a selected sequence of sample signals;
means for recording the selected sample signals in a storage medium at a first rate;
means for reproducing the same sample signals from the storage medium at a second rate which is slower than the first rate;
means for regenerating an audible signal from the reproduced signals, which audible signal contains the frequency characteristics of the original audible sounds, including original pitch, but stretched-in-time; and
selectively actuable control means coupled to control the recording means and the reproducing means to operate at different rates.
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Abstract
A system for recording heart sounds from a stethoscope-type device and reproducing selected heartbeats stretched out in time but with the same pitch as recorded. In one embodiment the heart sounds are sampled and converted to a digital representations which are recorded on a tape recorder at a first speed. The tape recorder is of the endless loop recording and playback type. At a signal from the user, the tape recorder plays back at a reduced speed the last few heartbeats which are recorded. These are converted to analog signals and fed back to the transducer in the stethoscope for reproduction as natural heartbeat sounds merely stretched in time.
Another system records the heartbeat sounds on a rotating recorder such as a magnetic drum. The magnetic transducer may be driven at variable speeds so that, when activated by the user, the speed of the playback transducer is reduced relative to the speed of the transducer during recording, without reducing the rotational speed of the drum. Thus, the pitch of the heart sounds is not affected, although they are stretched out in time.
Another embodiment utilizes a delay line for temporary storage with scanning of selected taps in the delay line for storage of selected samples in the memory. Upon activation by the user, the stored samples in the memory are read out at a reduced rate, filtered for smoothing, and fed back to the stethoscope transducer for reproduction as stretched heartbeat signals at the original pitch.
22 Citations
18 Claims
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1. Apparatus for reproducing sounds stretched-in-time comprising:
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sound transducer means for picking up audible sounds and generating corresponding electrical signals; means for processing said electrical signals to develop a selected sequence of sample signals; means for recording the selected sample signals in a storage medium at a first rate; means for reproducing the same sample signals from the storage medium at a second rate which is slower than the first rate; means for regenerating an audible signal from the reproduced signals, which audible signal contains the frequency characteristics of the original audible sounds, including original pitch, but stretched-in-time; and selectively actuable control means coupled to control the recording means and the reproducing means to operate at different rates. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A heart sound processing system comprising:
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a pickup for heart sounds; a transducer associated with said pickup for developing electrical signals corresponding to the heart sounds; means for recording and reproducing said electrical signals; means for selectively controlling the recording and reproducing means to record the signals in real time and to reproduce a selected portion of the recorded signals at a later time with original pitch but stretched-in-time; means for generating audible sounds from applied electrical signals; and means for selecting between the original heart sounds and the reproduced signal portion for application to a user'"'"'s ear.
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Specification