Humans can hear particularly well at these frequencies due to a resonance of the air volume in the ear canal. The threshold has different values at different frequencies. Tracing the lower limit (the hearing threshold), it is evident that the lower limit of hearing varies with frequency. The dip at about 4000 Hz is because the air volume in the ear canal goes into resonance which allows the ear to hear even low level sounds.
Sounds cannot be heard at the decibel levels and frequencies outside of the grey area. The human hearing domain is shown in Figure 1.įigure 1: The human hearing domain is both frequency and level dependent. In fact, there is a separate sound quality metric called loudness (with units sones or phons) which gives a much better representation of how humans perceive the level of a sound. Decibel (dB) values accurately represent the amplitude of a sound, but they do not accurately represent the perceived loudness of a sound. The decibel value is often used to quantify sound. Calculating Loudness in Simcenter Testlabĩ.3 Calculating Loudness in Signature Throughput Processing Sones takes into account the frequency and level dependent nature of human hearing, while decibels does not fully address this dependency.Ħ.3 Stationary Loudness Spectrum (Specific Loudness)ĩ.
Sones is a different unit of measure than the traditional decibel quantity. Sones is unit of measure of the loudness of a sound.