Left Loudspeakers Research Articles

Adaptation of Scoring Methods for Testing Cochlear Implant Users Using the Cantonese Hearing In Noise Test (CHINT)

It is often difficult to use an adaptive approach to evaluate speech reception in noise in cochlear implant (CI) users, because of variations in performance. Thus, two studies were conducted to develop an alternative method for scoring the Cantonese Hearing In Noise Test (CHINT) and to use this method for evaluating speech reception in CI users. In Study 1, 20 normal-hearing adults were tested using four scoring methods, including three modified and the standard HINT scoring method. The speech was presented in the front, and noise originated from the front, the right, or the left loudspeakers, as a standard HINT protocol. Threshold signal-to-noise ratio (S/N) and word intelligibility percent score (word score) were measured in each CHINT noise condition using each rule. In Study 2, depending on the word score of the individual CI user in the quiet CHINT condition, different adaptive rules were selected to score the responses from 12 CI users in the three noise conditions. The percentage of CI users who could successfully be tested using these scoring methods was evaluated. In Study 1, threshold S/Ns obtained using different rules were significantly different and consistent with expectations. The slopes of the performance-intensity function relating mean word scores and threshold S/Ns were linear and agreed well with previous findings. These results showed that the modified rules could be used to adaptively measure CHINT thresholds in noise. In Study 2, these modified rules were successful in measuring CHINT thresholds in 10 of the 12 participants, whose word scores in quiet exceeded 40%. These modified rules could be used in CI users whose speech reception ability could not have been measured otherwise.

Aging Effects on Detection of Spectral Changes Induced by a Break in Sound Correlation

Previous studies have shown that both younger adults and older adults with clinically normal hearing are able to detect a break in correlation (BIC) between interaurally correlated sounds presented over headphones. This ability to detect a BIC improved when the correlated sounds were presented over left and right loudspeakers rather than over left and right headphones, suggesting that additional spectral cues provided by comb filtering (caused by interference between the two channels) facilitate detection of the BIC. However, older adults receive significantly less benefit than younger adults from a switch to loudspeaker presentation. It is hypothesized that this is a result of an age-related reduction in the sensitivity to the monaural spectral cues provided by comb filtering. Two experiments were conducted in this study. Correlated white noises with a BIC in the temporal middle were presented from two spatially separated loudspeakers (positioned at ±45-degree azimuth) and recorded at the right ear of a Knowles Electronic Manikin for Acoustic Research (KEMAR). In Experiment 1, the waveforms recorded at the KEMAR's right ear were presented to the participant's right ear over a headphone in 14 younger adults and 24 older adults with clinically normal hearing. In Experiment 2, 8 of the 14 younger participants participated. Under the monaurally cueing condition, the waveforms recorded at the KEMAR's right ear were presented to the participant's right ear as Experiment 1. Under the binaurally cueing condition, waveforms delivered from the left loudspeaker and those from the right loudspeaker were recorded at the KEMAR's left and right ear, respectively, thereby eliminating the spectral ripple cue, and were presented to the participant's left and right ears, respectively. For each of the two experiments, the break duration threshold for detecting the BIC was examined when the interloudspeaker interval (delay) (ILI) was 0, 1, 2, or 4 msec (left loudspeaker leading). In Experiment 1, both younger participants and older participants detected the BIC in the waveforms recorded by the right ear of KEMAR, but older participants had higher detection thresholds than younger participants when the ILI was 0, 2, or 4 msec without an effect of SPL shift between 59 and 71 dB. In Experiment 2, each of the eight younger participants was able to detect the occurrence of the BIC in either the monaurally cueing or binaural-cueing condition. In addition, the detection threshold under the monaurally cueing condition was substantially the same as that under the binaurally cueing condition at each of the four ILIs. Younger adults and older adults with clinically normal hearing are able to detect the monaural spectral changes arising from comb filtering when a sudden drop in intersound correlation is introduced. However, younger adults are more sensitive than older adults are, at detecting the BIC. The findings suggest that older adults are less able than younger adults to detect a periodic ripple in the sound spectrum. This age-related ability reduction may contribute to older adults' difficulties in hearing under noisy, reverberant conditions.

Audio stereo processing method, device and system

The present invention relates to a method and a device for processing and reproducing an audio stereo signal. The method produces a left output signal for transmission to a left loudspeaker in a loudspeaker pair, which is, or is equivalent to, the sum of the mid input signal (M) and the side input signal (S), the method further produces a right output signal for transmission to a right loudspeaker in said pair, which is, or is equivalent to, the sum of the mid input signal (M) and the side signal (S) phase shifted 180° . The method further being characterized in that at least part of the side input signal (S) or the mid input signal (M) is phase shifted approximately 45°-135° relative to the other signal prior to or at the production of the left and right output signals. The invention further relates to such an audio stereo signal reproduction system.

Electronic musical instrument capable of reporting operating conditions including sound level and tempo

An electronic musical instrument capable of reporting a sound level and a tempo to be set. When a particular sound level or a particular tempo is selected and set, a click having a particular pitch matching the sound level or the tempo is generated to allow the user to recognize the sound level or the tempo on the basis of the pitch of the click. The instrument has a right and a left loudspeaker and, when the sound level is high or the tempo is fast, produces louder sound from one of the loudspeakers while, when the sound level is low or the tempo is slow, producing louder sound from the other loudspeaker.

Stereophonic reproduction system

A stereophonic reproduction system which improves an unnatural sound image localization at an asymmetric position relative to right and left loudspeakers. Deterioration in tone quality incidental thereto is improved by filters providing right and left channels with selected phase characteristics.

Pan-pot control apparatus

An input musical tone signal is amplified by a first VCA and then supplied to second and third VCAs. The second and third VCAs are controlled by sine-wave signals which have a 180°-phase difference. Musical tone signals, which have been so controlled that a pan-pot may move right and left, are supplied to right and left loudspeakers. The first VCA is controlled by a sine-wave signal whose phase is different by 90° from the phases of the signals supplied to the second and third VCAs. The volume of a composite musical tone made up of the tones generated by the loudspeakers is thereby controlled, thus also moving the pan-pot to the front and rearward.

The Franssen effect and the localization plausibility hypothesis

The Franssen effect is obtained with two loudspeakers in a room. If a sine tone is abruptly turned on at the left loudspeaker, then slowly faded off while the right loudspeaker is slowly faded on, a listener will judge that the tone continues to come from the left loudspeaker, even though the left loudspeaker is not sounding at all. Our own studies of localization of sound in rooms have led to a principle of localization called the “plausibility hypothesis.” One of the predictions of this hypothesis is that in an anechoic room the Franssen effect should fail [B. Rakerd and W. M. Hartmann, J. Acoust. Soc. Am. 78, 524–533 (1985)]. Experimental studies are reported using the Franssen stimulus both in an ordinary room and in an anechoic room. The results of the experiment support the prediction. [Work supported by the National Institutes of Health.]

4701952 Frequency attenuation compensated pneumatic headphone and liquid tube audio system for medical use

A confined system of sound transmission from a frequency attenuation compensated source through plastic pneumatic tubes in series with liquid tubes of considerable length, transmitting audio to and through pneumatic headphones to the ear canals of the user. It is an audio system suitable for use in Nuclear Magnetic Resonance scanning environments and for use in CAT scan environments. The system includes a stereo program source playing into a stereo frequency compensation amplifier driving right and left loudspeaker pneumatic drivers feeding audio to and through long liquid tubes in series with pneumatic tubes extended to left and right earphones of plastic headphones worn by a patient in a scan room environment. The tubes that extend from the electronic audio system equipment outside the scan room through scan room walls to the patient headphones and the headphones themselves are made of plastic or other non-magnetic materials causing no interference with the scanning signals and are not visible on scan pictures produced.