Quotables
"I watched his countenance closely, to see if he was not deranged ... and I was assured by other senators after he left the room that they had no confidence in it."
U.S. Senator Smith of Indiana ; After seeing Samuel Morse demonstrate the telegraph.
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| Number | Title | Issue Date |
| 4517415 | Hearing aids A hearing aid comprising a microphone whose output signal is split by high and low pass filters and supplied to two channels. Each channel includes a variable gain circuit the outputs of which are mixed and supplied to an earphone. The turnover frequencie... | 05/14/1985 |
| 4509022 | Amplifier circuit with automatic gain control and hearing aid equipped with such a circuit An amplifier system comprising an input transducer, an amplifier and an output transducer connected in cascade, and an automatic gain control circuit comprising a variable resistor for taking off a voltage which varies with the signal from the input trans... | 04/02/1985 |
| 4491980 | Hearing aid coupled with a radio A built in radio/hearing aid comprises a control voltage generator means which generates a control voltage depending on the level of a microphone signal of the hearing aid and a mixing control means which controls the ratio of the mixture of a radio signa... | 01/01/1985 |
| 4484345 | Prosthetic device for optimizing speech understanding through adjustable frequency spectrum responses Electronic circuitry for providing compensatory amplification to restore speech clarity for aurally handicapped persons comprising multiple active filters in a lowpass, bandpass, highpass (LP/BP/HP) configuration which provides composite filter responses ... | 11/20/1984 |
| 4475230 | Hearing aid In a hearing aid, when the input sound pressure to the microphone exceeds a preset level for a preset period of time, a control signal is produced to automatically decrease the maximum output sound level, thereby decreasing the overload to the user.... | 10/02/1984 |
| 4472603 | Portable communication apparatus A portable communication apparatus (10) for communication between a first person of normal hearing ability and a second person whose hearing is impaired is disclosed. The communication apparatus includes a first housing (12) enclosing a microphone and an ... | 09/18/1984 |
| 4454609 | Speech intelligibility enhancement In a communications system, consonant high frequency sounds are enhanced: the greater the high frequency content relative to the low, the more such high frequency content is boosted.... | 06/12/1984 |
| 4405831 | Apparatus for selective noise suppression for hearing aids Noise suppression apparatus is interposed between the transducer and the amplifier of a hearing aid, allowing the user to adjust the operation of an automatic level control circuit to provide suppression of background sounds with negligible effect on audi... | 09/20/1983 |
| 4396806 | Hearing aid amplifier A general purpose hearing aid amplifier is programmably adaptable to the prescription requirements of the hearing impaired. The hearing aid amplifier comprises a bank of bandpass-restricted channels, each channel having a voltage-controlled input amplifie... | 08/02/1983 |
| 4393275 | Hearing aid with controllable wide range of frequency response A hearing aid circuitry comprising a high pass filter and a low pass filter, for filtering the sound wave signals to permit adjustment of the gain of the high end of the frequency spectrum relative to its low end. The low pass filter is formed of a differ... | 07/12/1983 |
| 4366349 | Generalized signal processing hearing aid A generalized signal processing device for use as a hearing aid generates and modifies signals representative of acoustic patterns in a physiologically compatible manner which enables persons suffering from various auditory pathologies to recognize sound ... | 12/28/1982 |
| 4188667 | ARMA filter and method for designing the same A near minimum order ARMA type recursive filter with guaranteed stability and convergence is provided together with a method for obtaining the parameters of such filter. The amplitude/frequency response of the filter approximates an arbitrarily selected f... | 02/12/1980 |
| 4187413 | Hearing aid with digital processing for: correlation of signals from plural microphones, dynamic range control, or filtering using an erasable memory In an illustrated embodiment a behind-the-ear hearing aid includes a microphone, an amplifier-low pass filter circuit, an analog to digital converter, a digital integrated circuit arithmetic and logic unit for implementing a n-th order transfer function i... | 02/05/1980 |
| 4170720 | AGC circuit particularly for a hearing aid A high fidelity hearing aid is disclosed for providing high quality sound and is primarily directed to those users whose hearing loss is such that they need some amplification for low level signals, but do not need amplification for high level signals.... | 10/09/1979 |
| 4068090 | Hearing aid An improved hearing aid utilizing integrated field-effect transistors to reduce the size and power consumption thereof is provided. The hearing aid includes a microphone input device for producing signals representative of sound, an amplifier circuit for ... | 01/10/1978 |
| 4052571 | Hearing aid with amplitude compression achieved by clipping a modulated signal A hearing aid is arranged to restrict the dynamic range of the audio input signal to be compatible with the range which is characteristic of the hearing defect of the user. By means of phase-shift modulation for example, the input signal is converted to a... | 10/04/1977 |
| 4051331 | Speech coding hearing aid system utilizing formant frequency transformation A hearing aid system and method includes apparatus for receiving a spoken speech signal, apparatus coupled to the receiving apparatus for determining at successive intervals in the speech signal the frequency and amplitude of the largest formants, apparat... | 09/27/1977 |
