It is important to note that the different units are not comparable and are applied differently depending on the application. It is important to note that the a-weight is not suitable for all applications and that there are other weights that can be used for more specific applications, such as the c-weight or the z-weight. Long-term exposure to sound intensities above 85 dB(A) can damage the ears. It is a logarithmic scale, an increase of 10 corresponds to 10 times the intensity. The dB(A) unit is commonly used to measure sound intensities that are audible to the human ear. The decibel scale is a relative scale, based upon the threshold of hearing I0 10-12 W/m2. The human ear is more sensitive to certain frequencies than others, and a-weighting accounts for these differences by giving more weight to certain frequencies. The a-weighting was developed to better represent the sensitivity of human hearing. It is commonly used to measure the volume of ambient noise or music. dB(A): “dB(A)” stands for “decibel a-weighted” and refers to a type of sound level measurement used to indicate loudness in human hearing.It is also used to assess the quality of audio recording and playback devices and to ensure that the audio signal is not distorted during playback. The term dB FS is often used in relation to digital audio signals to indicate how loud or quiet the signal is compared to its maximum amplitude. A signal with a value of 0 dB FS thus has the maximum amplitude possible, while a signal with a value of -6 dB FS has half the maximum amplitude. When a signal is specified in dB FS, the amplitude of the signal is expressed in terms of that maximum amplitude. The term full scale (FS) refers to the maximum amplitude that a digital audio signal can have. It refers to the possible dynamic range of a digital audio signal encoded in a particular format. dB FS:”dB FS” stands for “decibels relative to full scale” and is often used in relation to digital audio signals.After settling into bed, you may hear your blood pulsing through your ears. (credit: Lingaraj G J, Flickr) In a quiet forest, you can sometimes hear a single leaf fall to the ground. It is often used to indicate the loudness of music or sounds that are audible to the human ear. Figure 17.11 Noise on crowded roadways like this one in Delhi makes it hard to hear others unless they shout.
1 Bel corresponds to an amplification of 10 dB. The Decibel Scale Concept Builder sharpens a learners understanding of the logarithmic nature of the deciBel scale. Bel: A unit used to measure the gain of electrical signals.
You could also use the approximation technique in reverse.There are also other units used for more specific applications.