The source also notes a subtle release at sākin kāf and tāʾ, describing its audible quality by resemblance to a trace of hāʾ, sīn or thāʾ. That is a description of a faint release, not replacement of the consonant itself.
Keep kāf as kāf and tāʾ as tāʾ, without turning them into other letters or adding a short vowel. The fine distinction is best checked with a qualified teacher.
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The subtle release of sākin kāf and tāʾ
Correct Vowel Articulation — Fatḥah, Kasrah, Ḍammah, Ishbāʿ and Sukūn
The source also notes a subtle release at sākin kāf and tāʾ, describing its audible quality by resemblance to a trace of hāʾ, sīn or thāʾ. That is a description of a faint release, not replacement of the consonant itself.
Keep kāf as kāf and tāʾ as tāʾ, without turning them into other letters or adding a short vowel. The fine distinction is best checked with a qualified teacher.