low pitch vs low frequency

low pitch and low frequency both are nouns.

Word	Noun	Adjective	Verb	Adverb
low pitch	Yes	No	No	No
low frequency	Yes	No	No	No

As nouns, low pitch and low frequency are synonyms defined as:

low pitch and low frequency: a pitch that is perceived as below other pitches

low pitch (noun)	low frequency (noun)
a pitch that is perceived as below other pitches	a pitch that is perceived as below other pitches
	30 to 300 kilohertz