The most basic characteristics of a sound wave are pitch, loudness and tone. A sound wave's frequency is experienced as the wave's pitch. The amplitude determines loudness or volume. The tone of a sound wave can be recognized by the regularity of its vibration.
A higher frequency has a higher pitch, whereas a lower frequency has a lower pitch. Human ears detect a large range of frequencies from to 20 to 20,000 Hz. When a sound is below a 20 Hz frequency range and inaudible to human hearing, it is called infrasound. Sounds above 20,000 Hz are known as ultrasound.
A larger amplitude means a louder sound, while a smaller amplitude means a softer sound. The sensitivity of an ear also determines the loudness of a sound, as human ears are more sensitive to certain frequencies than others. The volume of a sound is dependent on both a sound wave's amplitude and the more or less sensitive region of the ear that the frequency is picked up in.
While a simple tone has a single frequency, a complex tone is created from two or more simple tones. A sound's lowest-frequency tone is referred to as the fundamental tone, while the rest are called the overtones. If the overtones have frequencies that are whole multiples (2, 3, 4, etc.) of the fundamental frequency tone, they are called harmonics of the fundamental tone. A musical tone is the combination of these harmonic tones.