Activity . Fig. . : Sound Waves Amplitude one cycle Sound waves are described in terms of their frequency, which is measured in terms of cycles per second.
Its unit is called Hertz (Hz). Frequency and wavelength have an inverse relationship. When the wavelength increases, the frequency decreases, and when the wavelength decreases, the frequency increases. Amplitude and frequency both are physical dimensions.
Besides these, there are three psychological dimensions of sound, namely loudness, pitch and timbre. Loudness of the sound is determined by its amplitude. Sound waves with large amplitude are perceived as loud; those with small amplitude are perceived as soft. Loudness is measured in decibels (db).
Pitch refers to highness or lowness of a sound. The seven notes used in Indian classical music represent a gradual increase in their pitch. Frequency determines the pitch of a sound wave. The higher the frequency, the higher will be the pitch.
The range of hearing is generally Hz- , Hz. Timbre refers to the nature or quality of a sound. For example, the sound of a car engine and a person talking differ with respect to quality or timbre. The timbre of a A TTENTIONAL P ROCESSES In the previous section we have discussed some sensory modalities that help us in collecting information from the external world and also from our internal system.
A large number of stimuli impinge upon our sense organs simultaneously, but we do not notice all of them at the same time. Only a selected few of them are noticed. For example, when you enter your classroom you encounter several things in it, such as doors, walls, windows, paintings on walls, tables, chairs, students, schoolbags, water bottles, and so on, but you selectively focus only on one or two of them at one time. The process through which certain stimuli are selected from a group of others is generally referred to as attention.
At this point it may be noted that besides selection, attention also refers to several other properties like alertness, concentration, and search. Alertness refers to an individual’s readiness to deal with stimuli that appear