This may be a bit of a silly question, but it came up during playing and left me wondering. The spell description states that your voice booms "three times as loud as normal", but it leaves open how the volume of a voice is measured.
Two common ways to measure the volume of sound is to measure the pressure difference the sound causes as it travels through air and optionally to transform this level on a logarithmic scale (the Decibel scale). This table lists several things to reference. For example the upper end of a normal conversation sits at 0.02Pa or 60Db.
Now if we mean "three times as loud" on the linear pressure scale, that elevates a normal talking voice to the volume of a TV set. Not very impressive. If we mean "three times as loud" on the logarithmic scale, that comes out above the volume of a stun grenade. Very impressive, though probably a bit unbalanced for a cantrip.
Obviously neither of these interpretations is what the spell creator had in mind. But, then what is?