Based on the graph inFigure\({\bf{17}}.{\bf{36}}\), what is the threshold of hearing

in decibels for frequencies of\({\bf{60}},{\rm{ }}{\bf{400}},{\rm{ }}{\bf{1000}},{\rm{ }}{\bf{4000}},{\rm{ }}{\bf{and}}{\rm{ }}{\bf{15}},{\bf{000}}{\rm{ }}{\bf{Hz}}\)? Note

that many AC electrical appliances produce 60 Hz, music is commonly

\({\bf{400}}{\rm{ }}{\bf{Hz}}\), a reference frequency is\({\bf{1000}}{\rm{ }}{\bf{Hz}}\), your maximum sensitivity

is near\({\bf{4000}}{\rm{ }}{\bf{Hz}}\), and many older TVs produce a\({\bf{15}},{\bf{750}}{\rm{ }}{\bf{Hz}}\)whine.

The threshold of hearing is the minimum sound level below which a person can't hear any sound. and loudness for barely audible is 0phons

First, make a vertical line for all given frequencies and draw a horizontal line corresponding to these vertical lines then we will get our sound intensity levels in dB as shown in the figure.

This figure has a frequency(Hz) on the x-axis, intensity sound level (dB) on the y-axis, and a curved line showing the behavior of loudness(phons) corresponding to frequency and sound level.

• Here we are interested in points that are crossings of vertical lines and0-phon curve
• Now make horizontal lines corresponding to these points that are crossings of vertical lines and0-phon curve, this horizontal line will meet on the y-axis at some value of sound level.

We got the following from the figure.

• For\(400 Hz\)frequency, horizontal line cut y-axis around \(10 dB\) (threshold hearing)
• For\(1000 Hz\)frequency, horizontal line cut y-axis around \(0 dB\) (threshold hearing)
• For\(4000 Hz\)frequency, horizontal line cut y-axis around \( - 7 dB\) (threshold hearing)
• For\(15000 Hz\)frequency, horizontal line cut y-axis around \(20 dB\) (threshold hearing)