Al Lahn

Al-Lahn means alteration or mistakes in recitation. There are two types:
Making CLEAR mistakes اللَّحن الْجَلِى
Example: changing a letter or changing a sign (harakah), omitting or adding an extra letter of madd. These mistakes may change the meaning of the âyah. This type of mistake is harâm.
Examples: reading الضَّالِّينَ as الظالين, reading ثُمَّ as ثومَّ, reading أَنْعَمْتَ as أنعمتُ.
Making HIDDEN mistakes اللَّحن الخَفِى
Example: Ignoring ghunnah or subordinate madd.
Making CLEAR mistakes اللَّحن الْجَلِى
Example: changing a letter or changing a sign (harakah), omitting or adding an extra letter of madd. These mistakes may change the meaning of the âyah. This type of mistake is harâm.
Examples: reading الضَّالِّينَ as الظالين, reading ثُمَّ as ثومَّ, reading أَنْعَمْتَ as أنعمتُ.
Making HIDDEN mistakes اللَّحن الخَفِى
Example: Ignoring ghunnah or subordinate madd.