Showing papers on "Noise published in 1971"

Noise blanker circuit including rate bias and rate shutoff circuitry and audio blanking

Abstract: A noise blanking circuit for decreasing the impulse noise in a receiver includes a noise channel which develops blanking pulses in response to impulse noise. The noise pulses are coupled to a stage in the signal path for blanking the signals coupled therethrough to eliminate the reproduction of impulse noise. A rate shutoff circuit includes first and second timing circuits which are responsive to the repetition rate of the blanking pulses, and the duration of a series of pulses respectively, to develop a rate shutoff signal which inhibits the coupling of the blanking pulses to the blanking circuit. A rate bias circuit, coupled to the rate shutoff circuit, is responsive to the rate shutoff signal to develop a rate bias signal to maintain the gain of the noise amplifiers at a desired level. An audio blanking circuit is coupled to the rate shutoff circuit and the receiver squelch circuit and is responsive to the blanking pulses exceeding a predetermined rate and duration to develop an audio blanking pulse for inhibiting operation of the receiver audio circuitry. The audio blanking circuit further includes timing circuitry which is responsive to the blanking pulses exceeding a predetermined rate and duration to inhibit development of the audio blanking signal when the rate shutoff function is operative.

Hydrosonic diving communication amplifier system

Abstract: Intelligible audio communications between a diver and a surface boat, or from the occupant of a recompression chamber to the outside, are ensured by interposing an electronic system between a microphone and a speaker to block major portions of gas-flow noise generated as the gas is transferred. A preamplifier stage is electrically connected to the microphone, and a preamplifier filter defines the passband of composite signals composed of gasflow noise and audio communications. An attenuation stage receives the composite signals and further excludes signals lying outside the composite signals'' passband, and notches out high intensity gas-flow noise concentrated at a particular noise frequency predetermined by spectral analysis of the composite signal. Necessarily, a portion of the audio communications, centered about the noise frequency, is also blocked; however, the remainder is sufficient to enable reconstruction of intelligible speed at an interconnected speaker.

Angus and the ducks

Abstract: Angus was curious about everything, but he was especially curious about the noise which came from the other side of the hedge at the end of the garden. One day he decided he would find out what it was.

Muter for television receivers

Abstract: An intercarrier television receiver is provided with an audio amplifier normally biased beyond cutoff. A tuned circuit, separate from the intercarrier sound system of the receiver, is sharply tuned to the intercarrier frequency for selectively producing a control signal operative to unlock the audio amplifier. Limiters are provided to prevent unlocking of the audio amplifier in response to excessive noise pulses, and to maintain the control signal at a steady value regardless of changes in amplitude of the received signal.

Cross-Sensory Effects of White Noise on Color Perception.

Abstract: : The perceived intensity of red, green and blue lights was measured under conditions of dark-adaptation or nondark-adaptation and silence or 100 dB white noise. Sixty male subjects were randomly assigned over twelve experimental cells and required to match a colored light to a white standard. No significant differences were found between dark-adaptation and nondark-adaptation. Significant differences were found between the silence and noise conditions (p <.01) and between the three colors (<.001). Light sensitivity or perceived intensity was increased under the white noise conditions. The data are viewed as supporting theories of sensory interaction stressing the importance of considering vision and autition as interactive systems. Possible implications in human engineering design and subsequent research efforts are discussed. (Author)

Relative loudness judgments of non-shadowed material presented dichotically.

Abstract: Szrnmavy.-In a non-shadowing dichotic loudness judgment task, 20 Ss matched speech and white noise intensities at 60, 70, 80, 90, 100, and 110 db. Above 70 db, Ss judged speech to be louder than white noise, at 70 db they were judged to be equally loud, but at 60 db white noise was considered to be louder than speech. These findings are discussed in terms of the attenuabiliry of different types of material.

Jury Ratings of Complex Aircraft Noise Spectra Versus Calculated Ratings

Abstract: A set of 30 steady‐state noises, comprised of 15 recordings of aircraft engine noise and 15 filtered recordings, was presented to a group of 35 jurors. All noises were heard at a computed tone‐corrected perceived noise level of 90 PNdB, as specified by the new FAA noise certification rule. Jurors were asked to rate these noises against a single reference noise using a method‐of‐adjustment procedure. The resulting jury ratings spanned a 6‐dB range. Data are presented showing how this range was influenced by spectral characteristics of the noise which included both strong individual tones and multiple pure tones. Better correlations were obtained between jury ratings and the measure ANL, as described at the San Diego meeting.

Noise as Perceived by the Community

Abstract: Community aircraft noise intensity indexes from annoyance and physiological reaction standpoint, discussing sleep interruption, hearing loss, communication interference, etc

Studies on the masking of speech by white noise

Abstract: Authors studied the masking of speech (One-Syllable 100 Word List) by white noise. The following conclusions were reached:The curves of Speech Articulation Score shift to the right with increased intensity of masking noise. Davis' Social Adequacy Index (S.A.I.) derived from the curves of Speech Articulation Score revealed a sharp descent when the level of the sound pressure of noise increased.