observe the different sounds in your surroundings and prepare a table showing sounds having more pitch and Less pitch explain the reason
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Answers
Explanation:
oise sources and their measurement
2.1.Basic Aspects of Acoustical Measurements
Most environmental noises can be approximately described by one of several simple measures.
They are all derived from overall sound pressure levels, the variation of these levels with time
and the frequency of the sounds. Ford (1987) gives a more extensive review of various
environmental noise measures. Technical definitions are found in the glossary in Appendix 3.
2.1.1. Sound pressure level
The sound pressure level is a measure of the air vibrations that make up sound. All measured
sound pressures are referenced to a standard pressure that corresponds roughly to the threshold of
hearing at 1 000 Hz. Thus, the sound pressure level indicates how much greater the measured
sound is than this threshold of hearing. Because the human ear can detect a wide range of sound
pressure levels (10–102 Pascal (Pa)), they are measured on a logarithmic scale with units of
decibels (dB). A more technical definition of sound pressure level is found in the glossary.
The sound pressure levels of most noises vary with time. Consequently, in calculating some
measures of noise, the instantaneous pressure fluctuations must be integrated over some time
interval. To approximate the integration time of our hearing system, sound pressure meters have
a standard Fast response time, which corresponds to a time constant of 0.125 s. Thus, all
measurements of sound pressure levels and their variation over time should be made using the
Fast response time, to provide sound pressure measurements more representative of human
hearing. Sound pressure meters may also include a Slow response time with a time constant of 1
s, but its sole purpose is that one can more easily estimate the average value of rapidly
fluctuating levels. Many modern meters can integrate sound pressures over specified periods and
provide average values. It is not recommended that the Slow response time be used when
integrating sound pressure meters are available.
Because sound pressure levels are measured on a logarithmic scale they cannot be added or
averaged arithmetically. For example, adding two sounds of equal pressure levels results in a
total pressure level that is only 3 dB greater than each individual sound pressure level.
Consequently, when two sounds are combined the resulting sound pressure level will be
significantly greater than the individual sound levels only if the two sounds have similar pressure
levels. Details for combining sound pressure levels are given in Appendix 2.
2.1.2. Frequency and frequency weighting
The unit of frequency is the Hertz (Hz), and it refers to the number of vibrations per second of
the air in which the sound is propagating. For tonal sounds, frequency is associated with the
perception of pitch. For example, orchestras often tune to the frequency of 440 Hz. Most
environmental sounds, however, are made up of a complex mix of many different frequencies.
They may or may not have discrete frequency components superimposed on no