"mur du son" meaning in French

{
  "head_templates": [
    {
      "args": {
        "1": "m",
        "2": "-"
      },
      "expansion": "mur du son m (uncountable)",
      "name": "fr-noun"
    }
  ],
  "lang": "French",
  "lang_code": "fr",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "French entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "fr",
          "name": "Aviation",
          "orig": "fr:Aviation",
          "parents": [
            "Aeronautics",
            "Transport",
            "Sciences",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "examples": [
        {
          "english": "Are you trying to break the sound barrier driving at such high speed?!",
          "text": "Voulez vous percer le mur du son en conduisant à une vitesse si excessive?!",
          "type": "example"
        }
      ],
      "glosses": [
        "sound barrier (physical boundary)"
      ],
      "id": "en-mur_du_son-fr-noun-eGshZ2ja",
      "links": [
        [
          "sound barrier",
          "sound barrier"
        ]
      ],
      "tags": [
        "masculine",
        "uncountable"
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "/myʁ dy sɔ̃/"
    }
  ],
  "word": "mur du son"
}

{
  "head_templates": [
    {
      "args": {
        "1": "m",
        "2": "-"
      },
      "expansion": "mur du son m (uncountable)",
      "name": "fr-noun"
    }
  ],
  "lang": "French",
  "lang_code": "fr",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "French entries with incorrect language header",
        "French lemmas",
        "French masculine nouns",
        "French multiword terms",
        "French nouns",
        "French terms with IPA pronunciation",
        "French terms with usage examples",
        "French uncountable nouns",
        "Pages with 1 entry",
        "Pages with entries",
        "fr:Aviation"
      ],
      "examples": [
        {
          "english": "Are you trying to break the sound barrier driving at such high speed?!",
          "text": "Voulez vous percer le mur du son en conduisant à une vitesse si excessive?!",
          "type": "example"
        }
      ],
      "glosses": [
        "sound barrier (physical boundary)"
      ],
      "links": [
        [
          "sound barrier",
          "sound barrier"
        ]
      ],
      "tags": [
        "masculine",
        "uncountable"
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "/myʁ dy sɔ̃/"
    }
  ],
  "word": "mur du son"
}