How can we test whether two speech sounds are allophones of the same phoneme?

To determine whether two speech sounds are allophones of the same phoneme, checking for minimal pairs is the most effective method. Minimal pairs are pairs of words that differ by only one phoneme but have distinct meanings, such as "pat" and "bat." If two speech sounds can distinguish meaning when contrasting them in minimal pairs, they are considered separate phonemes rather than allophones. Conversely, if no such pairs can be found, it suggests that the two sounds are allophones of the same phoneme, as they do not create a difference in meaning when interchanged.

While analyzing frequency patterns, auditory discrimination, or measuring voice onset time can provide insights into the characteristics of speech sounds, they do not directly address whether two sounds function independently to signal differences in meaning. Therefore, the method of minimal pairs is the most definitive in identifying allophones.