Modifications are when you need the recording modified after delivery.
Modifications may be needed because you changed the script, wanted to provide different direction, or wanted to change a pronunciation.
Modifications are at-cost.
Ultimately, the cost for modifications varies depending on the request or specific project, but generally they are $10 per round (up to 50 words).
Email for for any modification requests and a quote.
Of course, if the recording contains a rare mistake (e.g., saying the wrong word), that correction is free.