“使咬字不清晰”可以翻译为 “make one's articulation unclear” 或 “cause one to articulate unclearly”。
“make one's articulation unclear” 强调直接导致咬字状态不清晰这一结果；
“cause one to articulate unclearly” 侧重于描述引发某人咬字不清晰这一行为或状态 。
例如：The cold made his articulation unclear.（感冒使他的咬字不清晰。）
The injury to his tongue caused him to articulate unclearly.（他舌头的伤导致他咬字不清晰 。）