Recording sessions can have many stops and starts, even with highly paid professional narrators. Inexperienced narrators find these interruptions unnerving. Newcomers to the studio are prone to focus on their own performance, rather than concentrate on connecting with a listener. That's natural, but anxiety comes through in anyone's voice. Likewise, fatigue, a cold induced hoarseness or nasality, coffee nerves, or other stresses will be recorded on tape.
Many authors improve quickly with rehearsal and voice coaching.
If an author will be performing his or her own material, a voice coach and lessons over several weeks can be a wise investment. Reading your own book is hard work. Few authors believe this the first time into the studio, but almost all agree afterwards. We all laughed, stretched, and congratulated each other on managing the recording sessions in record time. It had been hard work, for everyone.