In the International Phonetic Al<answer>p</answer>habet (IPA), as<answer>p</answer>irated consonants are written using the symbols for voiceless consonants followed by the as<answer>p</answer>iration modifier letter ⟨◌ʰ⟩, a su<answer>p</answer>erscri<answer>p</answer>t form of the symbol for the voiceless glottal fricative ⟨h⟩. For instance, ⟨<answer>p</answer>⟩ re<answer>p</answer>resents the voiceless bilabial sto<answer>p</answer>, and ⟨<answer>p</answer>ʰ⟩ re<answer>p</answer>resents the as<answer>p</answer>irated bilabial sto<answer>p</answer>.
What modifier indicates a voiceless bilabial stop?
p