सर्वे स्वरा घोषवन्तो बलवन्तो वक्तव्या इन्द्रे बलं ददानीति सर्व ऊष्माणोऽग्रस्ता अनिरस्ता विवृता वक्तव्याः प्रजापतेरात्मानं परिददानीति सर्वे स्पर्शा लेशेनानभिनिहिता वक्तव्या मृत्योरात्मानं परिहराणीति ॥ २.२२.५ ॥
In plain words
All the vowels are to be spoken full-voiced and strong, with the thought "Let me give strength to Indra." All the sibilants are to be spoken unswallowed, uncast-out and open, with the thought "Let me give myself over to Prajāpati." All the stops are to be spoken slowly and without running them together, with the thought "Let me keep myself back from Death."
The commentators
Chāndogyopaniṣadbhāṣyam· bhāṣya
यत इन्द्राद्यात्मान स्वरादय , अत सर्वे स्वरा घोषवन्त बलवन्तो वक्तव्या । तथा अहमिन्द्रे बल ददानि बलमाद- धानीति । तथा सर्वे ऊष्माण अग्रस्ता अन्तरप्रवेशिता अनिरस्ता बाहरप्रक्षिप्ता विवृता विवृतप्रयत्नोपेता । प्रजा- पतेरात्मान परिददानि प्रयच्छानीति । सर्वे स्पर्शा लेशेन शनकै अनभिनिहिता अनभिनिक्षिप्ता वक्तव्या । मृत्यो रात्मान बालानिव शनकै परिहरन् मृत्योरात्मान परिह राणीति ॥
In plain words
Since the vowels and other sounds have deities like Indra as their very essence, all vowels must be uttered with resonance and strength, with the thought: 'May I bestow strength, may I infuse strength into Indra.' Likewise, all sibilants must be uttered unswallowed—not drawn too far inward—and unrejected—not flung too far outward—and open, possessing the open vocal effort, thinking: 'May I entrust, may I surrender my self to Prajāpati.' And all stop consonants must be uttered very gently and without heavy pressure, thinking: 'Just as one carefully protects children, gently shielding my self from Death, may I protect my self.'
Close to the Sanskrit
Since Indra and others are selves the vowels and others, therefore all vowels sonorous strong to be spoken. Thus 'May I give strength in Indra, may I place strength'. And all sibilants unswallowed—brought inside, unrejected—flung outside, open—endowed with open effort. 'Prajāpati's self may I entrust, may I hand over'. All stops with a trace—gently, uncompressed—unplaced, to be spoken. 'Death's self—like children gently protecting—may I protect Death's self' thus.