The phrase "speak in the humblest accents" implies a sense of modesty and humility. Similar phrases or synonyms that convey the same idea could include "speak with deference," "speak with meekness," "speak in a submissive tone," or "speak in a self-effacing manner." The use of such language can suggest a desire to avoid coming across as arrogant or overly confident, instead prioritizing a tone of respect and deference. These phrases may be particularly relevant in professional settings or in situations where respect and deference are important social codes to observe.