He called for help at the top of his lungs and was finally heard.
Tips
usage
高声 is an adverb that modifies verbs of speech or sound: 高声唱 (sing loudly), 高声说话 (speak loudly), 高声呼喊 (shout). Compare with 大声 (dàshēng), which is more colloquial and interchangeable in most contexts.
