Auditory masking is when the perception of one sound is affected by the presence of another sound. Masking can be simultaneous or non simultaneous. For this discussion we will focus on simultaneous masking.<\/p>\n
This is when a signal, the sound that is desired to be heard, is made inaudible by a masker, noise or unwanted sound that is present throughout the signal.
A not masked threshold is the quietest level of the signal which can be perceived in quiet. Masked thresholds are the quietest level of the signal perceived when presented in noise. The amount of masking is the difference between the masked and not masked thresholds. For example if the masked threshold is 20dB and the not masked threshold is 35dB the amount of masking would be 15dB.<\/p>\n
The basic masking test involves the not masked thresholds being measured on a subject. Then the masking noise is introduced at a fixed sound level and the signal is presented at the same time. The level of the signal is varied until the new threshold is measured. This is the masked threshold.<\/p>\n
The phenomenon of masking is often used to investigate the auditory system’s ability to separate the components of a complex sound. For example if two sounds of two different frequencies (pitches) are played at the same time, two separate sounds can often be heard rather than a combination tone. This is otherwise known as frequency resolution or frequency selectivity. Frequency resolution is thought to occur due to filtering within the cochlea, the hearing organ in the inner ear. A complex sound is split into different frequency components and these components cause a peak in the pattern of vibration at a specific place on the basilar membrane within the cochlea. These components are then coded independently on the auditory nerve which transmits sound information to the brain. This individual coding only occurs if the frequency components are different enough in frequency, otherwise they are coded at the same place.<\/p>\n
Masking illustrates the limits of frequency selectivity even in a normal hearing person. If a signal is masked by a masker with a different frequency to the signal then the auditory system was unable to distinguish between the two frequencies. Therefore by carrying out an experiment to see the conditions which are necessary for one sound to mask a previously heard signal, the frequency selectivity of the auditory system can be investigated.<\/p>\n","protected":false},"featured_media":0,"template":"","categories":[],"tags":[],"storecat":[],"itemids":[],"manufacturers":[],"acf":[],"yoast_head":"\n\n\n\n\n\n\n\n\n\n\n\n\n\t\n