Characteristics of Sound

Name the unit in which the loudness of sound is expressed.

In a piano, pitch is decreased by:

The unit of loudness is:

The safe limit of loudness of audible sound is

If a drum is beaten hard, its loudness _____.

Smaller the membrane, _____ is the pitch.

The pitch of a flute is decreased by _____ length of air column.

The pitch of a stringed instrument is increased by _____ tension in string.

The time period of a wave is $2 \mathrm{s}$. Its frequency is _____.

The quality of a sound depends on the amplitude of wave.

Decibel is the unit of pitch of a sound.

The pitch of sound depends on frequency.

Name the characteristic of the sound affected due to a change in its
(a) amplitude (b) wave form (c) frequency.

How is the pitch of sound in a guitar changed if (a) thin wire is used, (b) wire under less tension is used?

Two identical guitars are played by two persons to give notes of the same pitch. Will they differ in quality ? Give reason for your answer.

Figure shows two jars A and B containing water up to different heights. Which will produce sound of higher pitch when air is blown on them ?

Figure shows four waves $A$, $B$, $C$ and $D$.
 
Name the wave which shows
(a) a note from a musical instrument,
(b) a soft note
(c) a shrill note.

Two waves have frequencies $256 \mathrm{Hz}$ and $512 \mathrm{Hz}$, but same amplitude. Compare their (i) loudness, and (ii) pitch.

Which characteristics of sound makes it possible to recognise a person by his voice without seeing him?

State the factors that determine
(a) the pitch of a note.
(b) the loudness of the sound heard.
(c) the quality of the note.