Sound II Reading

2.1. Pitch

Duration

Short pulses of a particular frequency can also be perceived as having a different pitch compared to a longer pulse of the same frequency – generally, a short pulse with decaying amplitude will be perceived as having a slightly higher pitch than a longer pulse of the same frequency.

Loudness

We now know that frequency can affect the perceived loudness of a signal, but it is also true that the actual signal volume can affect the perceived pitch; this can manifest itself in different ways. The level 60 dB SPL is considered to be a threshold where increases or decreases in loudness affect pitch perception. Above 60 dBm for sound below 2 kHz a substantial increase in loudness will cause an apparent lowering of the pitch, the sound will go flat. Similarly, a substantial increase in loudness levels above 2 kHz will cause the sound to appear sharp. If we decrease the loudness the opposite will occur. Below 60 dBm a decrease in loudness will cause sounds below 2 kHz to be perceived as getting sharp and sounds above 2 kHz perceived as going flat.