There are also options to adjust the frequency and tone of a call to suit their individual hearing needs.
ðɛɹˌɑːɹ ˈɔːlsoʊ ˈɑːpʃənz tʊ ɐdʒˈʌst ðə fɹˈiːkwənsi ænd tˈoʊn əvə kˈɔːl tə sˈuːt ðɛɹ ˌɪndᵻvˈɪdʒuːəl hˈɪɹɪŋ nˈiːdz.