* Studied the relationship between the length of a string and the pitch of the sound it produces.

* Discovered the concept of musical intervals.

* Developed the Pythagorean scale, which is based on the ratios of small whole numbers.

Aristotle (4th century BC)

* Wrote a book called "On the Generation of Animals" which contains the first known discussion of acoustics.

* Described the structure of the ear and the way in which it transmits sound waves to the brain.

* Studied the effects of different materials on the sound of musical instruments.

Theon of Smyrna (2nd century AD)

* Wrote a book called "On Music" which contains a detailed discussion of acoustics.

* Described the different types of sound waves and how they are produced.

* Studied the effects of different room shapes on the acoustics of musical performances.

Boethius (6th century AD)

* Wrote a book called "De Institutione Musica" which contains a summary of the work of previous acousticians.

* Developed a system for tuning musical instruments based on the Pythagorean scale.

* Studied the effects of different temperaments on the sound of musical instruments.