Category: (((—Acoustics Engineering—))))
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Annoyance
Noise consists of sounds that people do not enjoy and do not want to hear. However, it is difficult to relate the annoyance caused by noise to purely acoustical phenomena or descriptors. When people are forced to listen to noise against their will, they may find it annoying, and certainly if the sound pressure level…
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Sleep Disturbance
It is well known that noise can interfere with sleep. Not only is the level of the noise important for sleep interference to occur, but so is its spectral content, number and frequency of occurrences, and other factors. Even very quiet sounds such as dripping taps, ticking of clocks, and snoring of a spouse can…
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Introduction
Noise and vibration can have undesirable effects on people. At low sound pressure levels, noise may cause annoyance and sleep disturbance. At increased levels, noise begins to interfere with speech and other forms of communication; at still higher levels that are sustained over a long period of time in industrial and other occupational environments, noise…
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Speech Production
Since speech and hearing must be compatible, it is not surprising to find that the speech frequency range corresponds to the most sensitive region of the ear’s response (Section 4.3.2) and generally extends from 100 to 10 000 Hz. The general mechanism for speech generation involves the contraction of the chest muscles to force air out of…
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Presbycusis
Another form of sensory‐neural hearing loss is presbycusis. This loss in hearing sensitivity occurs in all societies. Figure 4.24 shows the shift in hearing threshold at different frequencies against age [52]. As can be seen, presbycusis mainly affects the high frequencies, above 2000 or 3000 Hz. It affects men more than women. The curves shown in Figure 4.24 show the…
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Sensory‐Neural Hearing Loss
There are several causes of sensory‐neural hearing loss and all are associated with disorders of the inner ear, the auditory nerve fibers, the auditory cortex in the brain, or combinations of all three. Unlike conductive deafness, sensory‐neural deafness is often most severe at higher frequencies. Background noise can thus mask the consonants in speech and…
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Conduction Hearing Loss
This normally manifests itself as a fairly uniform decrease in hearing over most frequencies. Background noise usually causes people to speak louder and those with conduction deafness can then often hear. This type of deafness can normally be overcome by a hearing aid with sufficient amplification. There are several causes of conduction deafness, some of…
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Hearing Loss and Diseases (Disorders)
Some are born with the severe handicap of deafness. Others suffer sudden hearing loss later in life or (much more commonly) gradually lose their hearing over a period of time. For all these persons, deafness is a crippling loss of one of the most important senses. Deafness can be very slight or complete. There are…
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Empirical Loudness Meter
Figure 4.23 shows a block diagram of an empirical Zwicker‐type dynamic loudness meter (DLM) that includes the spectral and temporal loudness processing portrayed in Figures 4.21 and 4.22 [22]. First, the spectral processing (1 and 2) shown in Figure 4.22 using the critical band filter bank concept, upward spread of masking (7), and spectral summation (8) are illustrated. Second, the temporal processing discussed in relation to Figure 4.23 is observed as shown in the…
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Loudness Adaptation
The term loudness adaptation refers to the apparent decrease in loudness that occurs when a subject is presented with a sound signal for a long period of time [45]. The effect has been studied extensively by presenting tones for an extended period of time to one ear and then allowing the subject to adjust the level of…