I often see that people confuse the two terms “length” and “duration”. In most cases, it doesn’t matter, but there are subtle differences one should be aware of. Here is a quick reference:
- length = a count (number of items, characters, samples, notes)
- duration = a time span (how long something lasts)
In music research, the difference matters! For example, if you ask about the “length of a piece of music”, it could refer to the number of notes in the score (e.g., 189 notes). The duration, however, would be the playback time (e.g., 3 minutes 20 seconds). Obviously, the playback time is related to the tempo, the same length of notes at different tempos yields different durations.
The same goes for digital audio. The length would here be the number of samples in a recording, while the duration is based on the sampling rate (Duration = samples / sample_rate).
In most cases people will understand. However, to ambiguity, try to be precise!