Aural tests are administered by the examiner from the piano. They are the same for all instruments, use the same group of tests, and are carefully graded from basic recognition of rhythm and memory of short phrases to tests demanding well-developed aural perception and discrimination. The pass mark is 12 and the maximum mark is 18.
For any test that requires a sung response, pitch rather than vocal quality is assessed. The examiner will be happy to adapt to your vocal range, and you can sing to any vowel (or consonant followed by a vowel), hum or whistle, and at a different octave if appropriate.